scholarly journals Estimated abundance and diversity of heterotrophic protists in South African biocrusts

2016 ◽  
Vol Volume 112 (Number 7/8) ◽  
Author(s):  
Kenneth Dumack ◽  
Robert Koller ◽  
Bettina Weber ◽  
Michael Bonkowski ◽  
◽  
...  
Keyword(s):  
South African ◽  
Soil Nutrient ◽  
Ecosystem Functions ◽  
Turnover Rates ◽  
Succulent Karoo ◽  
Functional Roles ◽  
Carbon And Nitrogen ◽  
Different Types ◽  
Abundance And Diversity ◽  
Soil Protists

Abstract Biological soil crusts (biocrusts) occur widely in the uppermost millimeters of the soil in arid and semi-arid systems. Worldwide they cover large terrestrial areas and play a major role in the global terrestrial carbon and nitrogen cycles. However, knowledge of the microbial decomposer foodwebs within biocrusts is particularly scarce. Heterotrophic protists in soil are predominantly bacterivores, and because of their high biomass compared with other soil fauna and fast turnover rates, protists are considered an important factor for soil nutrient cycling and energy fluxes. Thus, knowledge of their biodiversity, abundance and functional roles is important to understand soil ecosystem functions. We investigated the diversity and abundance of heterotrophic soil protists in different types of biocrusts from the Succulent Karoo, South Africa. With an overall diversity of 23 distinct morphotypes, soil protist biodiversity was shown to be high. The most abundant groups were Spumella-like chrysomonads, gliding bodonids, glissomonads and heteroloboseans. Protist abundance was highly variable among samples. The abundance and diversity did not differ significantly among different types of biocrusts, indicating that microscale differences, but not macroscopic soil crust builders (e.g. cyanobacteria, lichens and bryophytes), have a major impact on the protist community.

The carbon and nitrogen cost associated with the growth, reproductive and dormant phases of two South African semi-arid geophytic species of Gethyllis (Amaryllidaceae)

2013 ◽  
Vol 61 (7) ◽  
pp. 528 ◽  
Author(s):  
Christiaan Daniels ◽  
Wilfred Mabusela ◽  
Jeanine Marnewick ◽  
Alexander Valentine
Keyword(s):  
South African ◽  
Physiological Responses ◽  
Natural Habitat ◽  
Resource Utilisation ◽  
Growth Phases ◽  
Succulent Karoo ◽  
Reproductive Growth ◽  
Carbon And Nitrogen ◽  
Flower Production ◽  
Vegetative And Reproductive Growth

Gethyllis multifolia L.Bolus and G. villosa Thunb. (Family: Amaryllidaceae) are deciduous and bulbous geophytes that occur in the succulent Karoo biome of South Africa. Both species occupy the same natural habitat, but G. multifolia is threatened and G. villosa not. Both G. multifolia and G. villosa require seasonal bulb reserves for initial vegetative and reproductive growth. In spite of G. villosa having smaller bulbs than G. multifolia, both species produce similar flower sizes and weights. The aim of the present study was to determine the carbon and nitrogen costs of vegetative and reproductive growth during the phases of growth, senescence, reproduction and dormancy of these bulbous species. The rates, costs and efficiencies of biomass production during various growth phases of the two species were determined in a comparative experiment. The results show that in spite of a significantly smaller bulb, G. villosa produced more leaves per unit bulb mass and invested more carbon and nitrogen resources into the bulbs during senescence. G. villosa also had a higher flower production, relative to bulb weight, than did G. multifolia. These physiological responses suggest that G. villosa may be more efficient at carbon and nitrogen resource utilisation.

scholarly journals Species functional traits and abundance as drivers of multiplex ecological networks: first empirical quantification of inter-layer edge weights

2020 ◽  
Vol 287 (1939) ◽  
pp. 20202127
Author(s):  
S. Hervías-Parejo ◽  
C. Tur ◽  
R. Heleno ◽  
M. Nogales ◽  
S. Timóteo ◽  
...  
Keyword(s):  
Species Traits ◽  
Abundant Species ◽  
Modular Organization ◽  
Vertebrate Species ◽  
Multilayer Network ◽  
Functional Roles ◽  
Different Types ◽  
Seed Dispersers ◽  
Natural Communities

Many vertebrate species act as both plant pollinators and seed-dispersers, thus interconnecting these processes, particularly on islands. Ecological multilayer networks are a powerful tool to explore interdependencies between processes; however, quantifying the links between species engaging in different types of interactions (i.e. inter-layer edges) remains a great challenge. Here, we empirically measured inter-layer edge weights by quantifying the role of individually marked birds as both pollinators and seed-dispersers of Galápagos plant species over an entire year. Although most species (80%) engaged in both functions, we show that only a small proportion of individuals actually linked the two processes, highlighting the need to further consider intra-specific variability in individuals' functional roles. Furthermore, we found a high variation among species in linking both processes, i.e. some species contribute more than others to the modular organization of the multilayer network. Small and abundant species are particularly important for the cohesion of pollinator seed-dispersal networks, demonstrating the interplay between species traits and neutral processes structuring natural communities.

scholarly journals Global urban signatures of phenotypic change in animal and plant populations

2017 ◽  
Vol 114 (34) ◽  
pp. 8951-8956 ◽  
Author(s):  
Marina Alberti ◽  
Cristian Correa ◽  
John M. Marzluff ◽  
Andrew P. Hendry ◽  
Eric P. Palkovacs ◽  
...  
Keyword(s):  
Urban Development ◽  
Biotic Interactions ◽  
Well Being ◽  
Ecosystem Functions ◽  
Phenotypic Change ◽  
Functional Roles ◽  
Phenotypic Changes ◽  
Evolutionary Changes ◽  
Multiple Regions ◽  
Anthropogenic Systems

Humans challenge the phenotypic, genetic, and cultural makeup of species by affecting the fitness landscapes on which they evolve. Recent studies show that cities might play a major role in contemporary evolution by accelerating phenotypic changes in wildlife, including animals, plants, fungi, and other organisms. Many studies of ecoevolutionary change have focused on anthropogenic drivers, but none of these studies has specifically examined the role that urbanization plays in ecoevolution or explicitly examined its mechanisms. This paper presents evidence on the mechanisms linking urban development patterns to rapid evolutionary changes for species that play important functional roles in communities and ecosystems. Through a metaanalysis of experimental and observational studies reporting more than 1,600 phenotypic changes in species across multiple regions, we ask whether we can discriminate an urban signature of phenotypic change beyond the established natural baselines and other anthropogenic signals. We then assess the relative impact of five types of urban disturbances including habitat modifications, biotic interactions, habitat heterogeneity, novel disturbances, and social interactions. Our study shows a clear urban signal; rates of phenotypic change are greater in urbanizing systems compared with natural and nonurban anthropogenic systems. By explicitly linking urban development to traits that affect ecosystem function, we can map potential ecoevolutionary implications of emerging patterns of urban agglomerations and uncover insights for maintaining key ecosystem functions upon which the sustainability of human well-being depends.

scholarly journals Repatriation turnover revisited: A focus on South African multinational enterprises

2018 ◽  
Vol 21 (1) ◽  
Author(s):  
Christiaan J. Naude ◽  
A. Johan Vogel
Keyword(s):  
South African ◽  
Quantitative Study ◽  
Negative Correlation ◽  
Multinational Enterprises ◽  
Multinational Enterprise ◽  
First Year ◽  
Turnover Rates ◽  
Expatriate Managers ◽  
Positive Correlations ◽  
Spearman’S Correlation

Background: The topic of repatriation turnover as a major source of concern for repatriates and their multinational enterprise has been covered extensively in the literature over the years, with the literature showing that between 15% and 38% of repatriated expatriates leave the employment of their multinational enterprise within the first year after repatriation. However, no such study has focused on the repatriation of South African expatriates. Aim: The primary aim of this study was to determine if there is a correlation between the repatriation practices of South African multinational enterprises and their repatriation turnover rates. The secondary aim of the study was to determine why repatriated employees leave the employment of South African multinational enterprises. Method: This quantitative study surveyed 41 expatriate managers of South African multinational enterprises, with the Mann-Whitney U test and Spearman’s correlation coefficient being used to test for correlations between the repatriation practices of South African multinational enterprises and their repatriation turnover rates. Results: The results revealed positive correlations between appointing a mentor to an expatriate to assist with the repatriation process, conducting an orientation programme prior to repatriation and supporting the expatriate with various initiatives during repatriation and lower repatriation turnover rates. Meanwhile a negative correlation was found between when a multinational enterprise starts with an orientation programme prior to repatriation and repatriation turnover rates. Conclusion: These findings provide valuable insights for South African multinational enterprises into practices they can employ to reduce their repatriation turnover rates.

Different Types of Microbial Fuel Cell (MFC) Systems for Simultaneous Electricity Generation and Pollutant Removal

2015 ◽  
Vol 74 (3) ◽  
Author(s):  
S. M. Zain ◽  
N. L. Ching ◽  
S. Jusoh ◽  
S. Y. Yunus
Keyword(s):  
Nitrogen Removal ◽  
Continuous Flow ◽  
Electricity Generation ◽  
Pollutant Removal ◽  
Flow Mode ◽  
Oxidizing Agent ◽  
Batch Mode ◽  
Carbon And Nitrogen ◽  
Different Types ◽  
The Relationship

The aim of this study is to identify the relationship between the rate of electricity generation and the rate of carbon and nitrogen removal from wastewater using different MFC processes.  Determining whether the generation of electricity using MFC process could be related to the rate of pollutant removal from wastewater is noteworthy. Three types of MFC process configurations include the batch mode (SS), a continuous flow of influent with ferricyanide (PF) as the oxidizing agent and a continuous flow of influent with oxygen (PU) as the oxidizing agent. The highest quantity of electricity generation was achieved using the continuous flow mode with ferricyanide (0.833 V), followed by the continuous flow mode with oxygen (0.589 V) and the batch mode (0.352 V). The highest efficiency of carbon removal is also achieved by the continuous flow mode with ferricyanide (87%), followed by the continuous flow mode with oxygen (51%) and the batch mode (46%). Moreover, the continuous flow mode with ferricyanide produced the highest efficiency for nitrogen removal (63%), followed by the continuous flow mode with oxygen (54%) and the batch mode (27%).

scholarly journals How the Botswana International University of Science and Technology Library Engages its Stakeholders in Connecting Information Resources, Services, and Space

2020 ◽  
Vol 4 (3/4) ◽  
Author(s):  
Ayanda Agnes Lebele
Keyword(s):  
Science And Technology ◽  
Information Resources ◽  
Library Services ◽  
Access To Information ◽  
Functional Roles ◽  
Engagement Strategies ◽  
Different Types ◽  
International University

In the quest to develop more innovative customer-focused library services, the Botswana International University of Science and Technology (BIUST) Library embarked on the development of robust initiatives that involved the engagement of various stakeholders. The emerging consultative and engaging trend is premised on the key values of facilitating access to information and demand-driven inclusive library services. The paper presents how the BIUST Library engages stakeholders in the development of multiple and flexible opportunities to access and use information. In doing so, it describes the recreation of internal library structures, space, and processes in a way that accommodates and demonstrates the categories and functional roles of different types of library stakeholders. The paper further points to how the stakeholders’ cultures and systems create a divide or imbalance in the access and usage of library services. The paper also argues for a need to define library stakeholders and develop engagement strategies that are entity and initiative specific.

scholarly journals SOX9 Stem-Cell Factor: Clinical and Functional Relevance in Cancer

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Maribel Aguilar-Medina ◽  
Mariana Avendaño-Félix ◽  
Erik Lizárraga-Verdugo ◽  
Mercedes Bermúdez ◽  
José Geovanni Romero-Quintana ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Stem Cell Factor ◽  
Current Knowledge ◽  
Functional Roles ◽  
Novel Treatments ◽  
Specific Subset ◽  
Different Types ◽  
Undifferentiated Cells ◽  
Functional Relevance

Transcriptional and epigenetic embryonic programs can be reactivated in cancer cells. As result, a specific subset of undifferentiated cells with stem-cells properties emerges and drives tumorigenesis. Recent findings have shown that ectoderm- and endoderm-derived tissues continue expressing stem-cells related transcription factors of the SOX-family of proteins such as SOX2 and SOX9 which have been implicated in the presence of cancer stem-like cells (CSCs) in tumors. Currently, there is enough evidence suggesting an oncogenic role for SOX9 in different types of human cancers. This review provides a summary of the current knowledge about the involvement of SOX9 in development and progression of cancer. Understanding the functional roles of SOX9 and clinical relevance is crucial for developing novel treatments targeting CSCs in cancer.

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